Vim keybindings don't unmap for editor.keys.vim.normal.cm (formerly map-keys behavior)

[cldwalker]

If a keybinding is added under :editor.keys.vim.normal.cm or :editor.keys.vim.visual.cm, these keybindings aren't unbound if they are commented which is not normal LT keybinding behavior. This happens because these tags don't use LT's keyhandling and instead interact directly with Vim's keymap. To unmap, we should unmap the last keys that were used. Unfortunately unmap() is not available, only map(). Once we're unblocked by #45, we should discuss and send a PR upstream to allow us to unmap Vim keybindings